The skull crusher is an exercise
for isolating the triceps. The triceps brachii is composed
of three heads. The three heads of the triceps have separate
attachments near the shoulder but a singular attachment for
each muscle just below the elbow. Even though body mechanics
don’t allow for complete isolation of any one given
head, you can slightly shift the emphasis from one head to
another by using a variety of exercises and angles. Good exercises
for well defined and stong triceps include dips, overhead
press, skull crushers, chest press, bench press, shoulder
press and lateral raise.